The present invention relates to a thermo box for transporting fresh goods such as fresh fish and meat, medicines etc. comprising a double sidewall, top and bottom construction of thermoplastic material, where the hollow space of a base portion, defining the bottom of the box, the sidewalls and the cover is filled with air or some other gas. A drainage for liquid such as icewater and/or juices from the goods is provided in conjunction with the base portion. The invention also comprises a method for producing a flat hollow moulding from which the box is shaped.
Particularly within the biomarine field, there has been an increase in the transportation of fish and shellfish as fresh food to consumers. Fish or shellfish are covered with ice and transported in insulated boxes, so called thermo boxes, to destinations at home or abroad.
The most ordinary boxes used for such transport today are made of foam plastic, for instance polystyrene. Although the thermal insulation ability for such boxes is good, the quality of the boxes in other aspects is poor. The constructional properties are poor; the boxes often break when stocked or carried, and as a consequence damage the contents, resulting in economic losses.
Foam plastic boxes also have the disadvantage of having through holes in the bottom at the sides, in order to drain liquids such as melted ice and blood exuding from the fish, and are as such essential. These holes, however, do not solve the undesirable problem of polluting the boxes' environments, such as stock and transport rooms. In airtransport it is highly preferable that goods be packed in waterproof containers. This requires that the base portion be provided with an additional material having a high absorption capacity. The extra packing increases the transportation costs, because the transportation capacity is reduced (due to the augmented volume) and repacking of the foam plastic containers is necessary.
In addition, the holes in the foam plastic containers contribute to a reduction of the insulation ability as air intrudes through the holes and circulates in the containers.
According to requirements of various national authorities, packing containers provided for the transportation of fresh food such as fish and meat can be used only once. An essential part of the disposable packing used for such transport will promptly be destroyed. Foam plastic containers represent a special environmental problem, as toxic dioxide is produced during combustion. For the recipient of the delivered goods, there is the problem of getting rid of the waste packing. It also ought to be mentioned that users of the foam plastic boxes are charged additionally for the transport of empty packing, as boxes of this type are quite voluminous.
Besides the above-mentioned foam plastic boxes which today are in practical use, another thermoplastic box is disclosed in German publication No. 2 226 970, but is presumably not commercially applied. The thermo box according to the German publication includes an inflatable, doublewall foil construction of a synthetic substance, for instance polyamid polyethylene, a base part having a perforated sheet allowing drainage of waste water. In an attempt to solve the stocking problem, the boxes are filled with a gaseous medium. It is quite apparent that the boxes will not be very useful when stacked. If one of the lowest boxes of a stack is punctured, which is not unlikely as trucks often are used, the whole stack will collapse. The drainage sheet in the base part of the box might fulfill its purpose as long as the box is not moved. But once the box is moved or is put in an oblique position, an undesirable flow of drainage of liquids may touch and contaminate the food.